15. EMERGENCY STATES

Emergency states are serious life-threatening morbid conditions of the body that develop under the effects of external and internal factors of extreme intensity. They include: collapse, coma and shock.

COLLAPSE

Collapse is an acute pathological condition that results from the significant discrepancy between the circulating blood volume and the total capacity of the peripheral vasculature. Thus, the most significant manifestation of collapse is acute decline in systemic arterial blood pressure. Based on the origin several types of collapses can be distinguished (fig. 16).

Fig. 16

Collapse is characterized by circulatory insufficiency, primary circulatory hypoxia, and systemic functional failure of organs and tissues. Collapse may rapidly lead to coma or may progress to shock.

COMA

Coma is an unconscious state from which the patient cannot be aroused by any external stimulus. Cardiovascular, thermoregulatory and neuroendocrine control is not preserved.

Coma may result from widespread damage in both hemispheres, suppression of cerebral function and brainstem lesions. Destructive lesions affecting the brainstem and adjacent structures of the upper pons, midbrain, and diencephalon may produce coma.

Local lesions confined to the cerebral hemispheres do not immediately affect the brainstem reticular activating system (RAS). Secondary dysfunction of the brainstem and diencephalic RAS results from compression by a mass in a cerebral hemisphere induced by brain edema or intracranial hemorrhage. Compression of midbrain, than the pons, and finally the medulla leads to sequential appearance of neurological symptoms and to progressively diminished alertness.